The Senate Foreign Relations Committee has approved a resolution authorizing limited U.S. participation in the NATO-led military campaign over Libya for one year. The House of Representatives voted down the measure last week. Tuesday’s committee vote followed a lively debate over presidential authority in ordering U.S. military intervention.

By a vote of 14 to 5, the Foreign Relations Committee approved the resolution after adopting language specifying that the United States will bear no reconstruction costs and deploy no ground forces in a post-Gadhafi Libya.

Hours earlier, lawmakers grappled with a basic question: What does it mean to be at war? The issue has been hotly debated since President Barack Obama ordered U.S. military intervention in Libya. The administration argues that the Libya mission is limited in scope, does not involve active military hostilities or U.S. ground forces, and therefore requires no approval by Congress.

At issue is the War Powers Resolution of 1973, which gives U.S. administrations 60 days to secure congressional authorization to engage in hostilities abroad, and an additional 30 days to withdraw forces if no authorization is granted. The Libya mission crossed the 90-day threshold earlier this month.

The Chairman of the Senate Foreign Relations Committee, Democrat John Kerry, says there is no comparison between the U.S. engagement in Libya and the Vietnam War of the 1960s and '70s - a protracted, undeclared war that spawned the War Powers Resolution. “Our involvement in Libya is obviously, clearly different from our fight in Vietnam. It is a very limited operation. In Libya today, no American is being shot at, no American troops are on the ground, and we are not going to put them there," he said.

That view was echoed by the State Department’s top legal advisor, Harold Koh, who testified before the committee.

“We are far from the core case that most members of Congress had in mind when they passed the [War Powers R]esolution in 1973. They were concerned then about no more Vietnams. But we do not believe that the 1973 Congress intended that its resolution should be construed so rigidly to stop the president from directing supporting action in a NATO-led, [U.N.] Security Council-authorized operation [in Libya] with international approval," he said.

Koh was challenged by the ranking Republican on the committee, Senator Richard Lugar. “The fact that we are leaving most of the shooting [over Libya] to other countries does not mean that the United States is not involved in acts of war," he said.

Lugar argued that if another country were taking part in a bombing campaign over the United States, the American public would consider it an act of war. He accused President Obama of casting aside his legal and constitutional duties as commander-in-chief. “President Obama made a deliberate decision not to seek a congressional authorization of his action -- either before it commenced or during the last three months. The president does not have the authority to substitute his judgment for constitutional process when there is no emergency that threatens the United States and our vital interests," he said.

Senator Kerry noted that many presidents have deployed U.S. military assets to conflict zones without congressional approval.

State Department legal advisor Koh said the question Congress faces is not a constitutional issue, but a policy matter. “Will Congress provide its support for NATO’s mission in Libya at this pivotal juncture," he said, "ensuring that [leader Moammar] Gadhafi does not gain the upper hand against the people of Libya?”

The Obama administration maintains that it does not need congressional approval to proceed in Libya, but it welcomes the resolution approved by the Foreign Relations Committee, which still faces a vote by the full Senate. While voting against authorization last week, the House of Representatives declined to cut off funding for the Libya operation.

Some lawmakers took issue with the administration’s reasoning that dropping bombs over Libya with no return fire constitutes a lack of hostilities.

Republican Senator Bob Corker said, “By that reasoning, we could drop a nuclear bomb in Tripoli, and we would not be involved in hostilities.”

In response to such criticisms, Senator Kerry suggested that the nearly 40-year-old War Powers Resolution might need to be updated. “It is true, of course, that the War Powers Resolution was not drafted with [remote-controlled aerial] drones in mind. As our military technology becomes more and more advanced, it may well be that the language needs further clarification. Maybe it is up to us to redefine it in the context of this more modern and changed warfare and threat," he said.

From the start, the War Powers Resolution has drawn heated legal debate. Some scholars argue that it unconstitutionally infringes on the president’s authority as commander-in-chief. Others have defended the measure as consistent with Congress’ authority to declare war. As Libya and other conflicts demonstrate, the resolution has not prevented the United States from deploying troops abroad in a wide variety of situations.